Lines and Angles (b)

THINGS TO DO

You should have five obtuse Isotiles.

Arrange all five so that each has the small base angle (marked '1' in the picture) meeting at the same point. They should form a straight line, with five equal angles at the same point. This allows you to work out the value in degrees of the angle marked '1'. Clue: what must they all add up to if they make a straight line?

Now put one Isotile down as shown on the left, then add an Isotile the other way up on either side, each touching the central one. You should have another straight line. Now you can work out the size of the angle marked '3'.

You now know the value of each angle. Add the three values together. What do they come to?

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